Data transferring system comprising an input-output channel unit capable of predicting an overrun in a data processing device

Claim 1

In a data transferring system for use in carrying out data transfer between a peripheral controller and an input-output channel unit in a data processing device comprising a data line, a start informing signal line, a start informing acknowledgement signal line, a strobe pulse signal line, and a strobe pulse acknowledgement signal line, said peripheral controller comprising: strobe pulse signal generating means for producing a strobe pulse signal and for delivering said strobe pulse signal to said strobe pulse signal line; signal producing means for producing, during a preselected time interval, a start code signal having a start code representative of a start of said data transfer and for producing, during production of said start code signal, a start informing signal for use in informing said input-output channel unit of production of said start code signal, said signal producing means being for delivering said start informing signal to said start informing signal line; and first memorizing means connected to said signal producing means and said data line for periodically memorizing said start code signal as a memorized code signal at a first period determined by a strobe pulse acknowledgement signal and for delivering said memorized code signal to said data line; said input-output channel unit comprising: first receiving means connected to said start informing signal line for receiving said start informing signal as a received informing signal; first transmitting means connected to said first receiving means and said start informing acknowledgement signal line for transmitting said received informing signal to said start informing acknowledgement signal line as a start informing acknowledgement signal; registering means connected to said data line and said first receiving means and enabled by said received informing signal for registering said memorized code signal as a registered code signal; second receiving means connected to said strobe pulse signal line for receiving said strobe pulse signal as a received pulse signal; second transmitting means connected to said second receiving means and said strobe pulse acknowledgement signal line for transmitting said received pulse signal to said strobe pulse acknowledgement signal line as said strobe pulse acknowledgement signal; and second memorizing means connected to said data line, said second receiving means, and a main memory; said first memorizing means being connected to a peripheral device; said first and said second memorizing means being for use in transferring transfer data between said main memory and said peripheral device through said data line after said registering means registers said memorized code signal, said first and said second memorizing means being for memorizing said transfer data as first and second memorized data at said first period and a second period determined by said received pulse signal; the improvement wherein: said input-output channel unit comprises: overrun predicting means connected to said second memorizing means for predicting occurrence of an overrun on the basis of an amount of said second memorized data to produce an overrun prediction signal; said first transmitting means being connected to said overrun predicting means for transmitting said overrun prediction signal to said start informing acknowledgement signal line; said peripheral controller comprising: strobe inhibiting means connected to said start informing acknowledgement signal line, said strobe pulse signal generating means, and said strobe pulse signal line and responsive to said overrun prediction signal for inhibiting delivery of said strobe pulse signal to said strobe pulse signal line during a predetermined time interval.